IMPROVEMENT OF MULTIPLE OVULATION TECHNOLOGY FOR THE PURPOSE OF OBTAINING DATED EMBRYOS IN SHEEP

Abstract

The article presents the results of preconceptual study on the development
of an optimal scheme for hormonal induction of polyovulation; determining the time and
mode of obtaining fertilized oocytes at the stage of two pronuclei for microinjection of the
gene construct. 24 adult clinically healthy sheep were used in the study. In order to prolong
the luteal phase and synchronize the estrous cycle, sheep donors were treated with intravaginal pessaries soaked with 45 mg of flugestone acetate. Folltropin -V was used as a folliculogenesis stimulator at a total dose of 220 mg. Instant access to the internal genital organs was
achieved through a ventral midline laparotomy. All sheep donors (100%) entered estrus, but
only 19 animals (79,2%) were found to have multiple ovulation. It was found that the average
time period from removal of the pessary to onset of estrus was 15,3 hours with wide variations from 9 to 29 hours. The average time period from removal of the pessary to the completion of estrus signs was 42,7 hours, with variability from 31 to 50 hours. The average duration
of estrus in the donor group was 27,2 hours, with variability ranging from 9 to 41 hours. In
total, 117 gametes (6,16 cells from 1 donor) were obtained from 19 donors with polyovulation. At the same time, 32 unfertilized oocytes were found (27,4% or 1,68 per donor). 50 cells
were identified at the stage of two pronuclei (42,7% or 2,6 per donor). Also, there were 35
other cells (29,9 % or 1,8 per donor). The obtained data do not allow us to identify and justify
clear criteria for the timing of operative measure to obtain fertilized eggs at the stage of two
pronuclei. However, based on the analysis of the obtained data, it can be stated that to calculate the time of gamete retrieval at a certain stage of development in sheep, parameters such as
the onset of estrus and the duration of estrus have priority. These parameters were obtained
experimentally and could serve as a guideline when carrying out a work on obtaining gametes
at the stage of two pronuclei.